1. Field of the Invention
The present invention relates a ratchet wheel structure, and more particularly to a ratchet wheel structure applicable for various kinds of screw devices.
2. Description of the Related Art
Referring to FIG. 17 for a prior art ratchet wheel structure, a ratchet wheel 60 is pivotally coupled to a wrench, and the ratchet wheel 60 includes a polygonal groove 61, which is generally in a dodecagonal shape or a hexagonal shape for turning a hexagonal screw device. However, the prior art has the following shortcomings:
If the polygonal groove 61 comes with a different shape, then the wrench can only work for a compatible screw device, and such wrench has a poor expandability.
Further, the wrench disclosed in U.S. Pat. No. 5,295,422 also has a poor expandability.